Thomas Wernberg1
1The University of Western Australia, Australia - 2Institute of Marine Research, Norway
Marine heatwaves (MHWs) have emerged as pervasive and destructive manifestations of anthropogenic climate change in our oceans. Temperature influences all aspects of biology, from gene expression to the global distribution of biomes, and MHWs often disrupt species and ecosystems because they create severe stress beyond past experience. Kelp forests are among the marine ecosystems most vulnerable to climate change, and their loss is increasingly attributed to MHWs. In this talk, I will show how warming and MHWs have impacted kelp, kelp forests and kelp-derived ecosystem services. I will present seascape genomics and ecophysiological studies that reveal selective pressures of warming and MHWs, and changes at the genetic and cellular level of kelps. At the population level, MHWs have caused subtle changes in population structure, abundance and function, and in some cases long-term collapse and local extinction of kelp forests. Some of the most dramatic effects of MHWs on kelp forests have been due to indirect effects from altered species interactions such as increased herbivory. Yet, MHW impacts are often influenced by their geographic, oceanographic or biological context, and some kelp forests show resilience to these events. MHWs do not occur in isolation from other pressures and have been shown to interact with human activities in the coastal zone, such as coastal darkening and overfishing. MHWs are now a reality of the Anthropocene and many kelp forests will decline as a consequence, with negative knock-on effects on the many benefits humans derive kelp forests. These projected losses are valued in the billions for the foreseeable future. The coming decades, and possibly the future prosperity and well-being of humanity, will be defined by our decisions on the conservation, restoration and sustainable use of ecosystems, including kelp forests. I will finish by highlighting the overwhelming mismatch between scales of kelp forest loss and repair. It is clear that even if there is growing activity and promising new approaches to upscale restoration and future-proof kelp forests, we will not close this gap. To truly turn the negative trend for the world’s kelp forests we must take action to avoid further loss and rethink the ocean optimism of nature-repair.
Biography
Thomas is an ARC Laureate Fellow and a professor of Marine Botany who studies seaweed forests and climate change. He heads the Wernberg Lab (wernberglab.org), at the University of Western Australia, and he is a Principal Scientist at the Norwegian Institute of Marine Research. Thomas is an editor-in-chief for the journal Aquatic Botany, he is a Clarivate highly cited scientist and ranked among the top 200 most influential climate scientists in the world by Reuters.